1. Field of the Invention
The present invention relates to an apparatus for displaying wiring which can graphically display correspondence between a plan wiring diagram of an electric circuit and a geographical layout diagram which represents layout of wirings in an actual machine or apparatus.
2. Description of the Related Art
Instruction manuals such as automotive service manuals contain a plan wiring diagram showing an electrical system and a three-dimensional layout diagram showing a geographical layout of wirings in illustrations of an automobile. Both manuals are referred to during servicing of the automobile.
Recently, plan wiring diagrams and geographical layout diagrams have become very complicated leading to a practice of referring to a service manual on a display screen. The service manual is converted into an electronic form. In a service manual in electronic form, a wiring diagram and a circuit board with electronic components mounted are displayed together in a split display screen or a position in the layout diagram corresponding to a position selected by a user in the plan wiring diagram is displayed in a different color, for example, as shown in Japanese Patent Application Publication No. 2005-4726.
However, plan wiring diagrams represent electrical relationships among components of an electrical system while three-dimensional layout diagrams represent relationships between positions and wirings of parts. The two types of diagram differ completely in the form of expression. It is difficult to watch the two diagrams alternately by shifting one's line of sight and understand the correspondence between the two diagrams.
In automobiles, wirings are often bundled into a wiring harness. Difficulty is also encountered in finding out where the plurality of wirings contained in the harness is located in a plan wiring diagram. Further, a single wiring connector or a single electrical component with multiple functions may be split into multiple portions and is displayed at multiple locations in a plan wiring diagram. This makes it difficult to recognize the wiring connector or electrical component. When similar parts are placed in a concentrated manner such as when a plurality of electronic control units (ECU) are placed in layers, it is not easy to distinguish the parts.